Had a lot of issues with my car and posted about it here before. Now the ambient temperature is starting to drop and I’m doing lots of short journeys to work I’m noticing the issues again with the gearbox which I wont go over again. However I’ve discovered the following:

When started from cold, the idle is usually about 900rpm no matter the weather, then it takes about 20 mins of driving for everything to warm up. Then no more clutch pack/gear issues.

Sometimes when starting from cold, the idle is about 1100 and gradually decreases to 900 after about 30 secs. When it starts like this I dont experience anywhere near as many issues with the gearbox or clutch pack.

A way around it is to start the car with the accelerator on the floor, and immediately lift off as it starts. This seems to make the idle at 1100 before gradually decreasing to 900 after about 30 secs everytime. As above, when it start up like this it runs so much better.

Any ideas? The car doesn’t have a MAF sensor so not that. Petrol so not a DPF. I’m determined to fix this as I cant find another car that suits my needs.

Throttle pot?

Sorry, didn’t see the original thread so this may be miles off.

You can’t fix it unless you can diagnose it. Posting vague descriptions of symptoms on the internet is not going to lead to a diagnosis, just random guessing. You need to take it to a workshop that can give you a proper diagnosis of all the problems with it. Then you can get some idea of what it will cost to fix it. It’s very likely that it won’t be economical to fix, in which case you should scrap it and buy something that isn’t knackered.

The cars 4 years old. 14k miles. 1.2 DSG. In 3rd gear the car kind of stutters at certain rpm. Almost like clutch slip or your foot slips of the throttle for half a second. Doesn’t do it after about 20 mins of driving.

Sometimes, maybe 1 in every 10 days, it doesn’t have any issues at all. That’s when I noticed the different idle speeds.

Dealers dont want to know. Tried and exhausted that one. Independent mechanic could feel the issue but couldn’t diagnose it.

I’m doing lots of short journeys to work

You need an expert to diagnose it with the benefit of live data. Not desperately expensive provided you avoid the dealer, but if the gearbox is misbehaving then it’s going to be expensive regardless.

Alternatively, stop using your car for short journeys and ride a bike to work?

Tricky one – could be anything and without some software to look at the data coming from the sensors when you get the issue you’re kind of stabbing in the dark.

If it were mine, I would take it for an italian tune up (ie a long , high revs drive, I mean high revs, bouncing off the limiter type revs) and see if that clears it, if that doesnt work then change the spark plugs (they’re cheap), if that doesnt work then I might be tempted to either live with the issue, or just sell the car if its a major problem to you.

If coil packs were cheap (I suspect theyre not) then I might also be tempted to replace the coil packs – but you’re just getting into parts roulette here.

I’d be checking the resistance values if the engine coolant temp sensor for starters. (Not the one for the dash gauge, the one for the ECU)*

*I only have old cars. Anything newish may use a combined sensor…

I’d be checking the resistance values if the engine coolant temp sensor for starters. (Not the one for the dash gauge, the one for the ECU)*

*I only have old cars. Anything newish may use a combined sensor…

On most (all? Def for VW & Ford since mid/late 200x’s) modern cars, the instrument cluster temp gauge will be displaying a “processed” version of the temperature the PCM[1] is sending. It will generally point to a fixed, central, position for all temps between about 75degC and 110degC.

As for the “high idle” when starting with foot to the floor, shortly followed by dropping to normal idle speed, that could well be the PCM just sorting out what is happening following a non-standard start, with far higher airflow than normal. Not knowing what car, or the age, makes it hard to guess what’s wrong, but it sounds like the forced higher idle is helping to mask whatever is wrong with the transmission.

If you start the car normally (foot off of the acc. pedal), and then use acc pedal to up the revs to 1100 for 30secs do you get the same improvement?

Some most recent petrol cars do have a particulate filter, and don’t assume that because it is petrol it doesn’t have a DMF – both my 2.0l and 3.0l Mondeo’s has one, 2005 vintage.

1. PCM = Powertrain Control Module, the box that controls the engine, and sometimes the gearbox. In the automotive development world, an ECU generally refers to Electronic Control Unit, of which modern cars have loads.

If you start the car normally (foot off of the acc. pedal), and then use acc pedal to up the revs to 1100 for 30secs do you get the same improvement?

No. Every other can I’ve owned starts with an idle around 1100 and drops after several seconds. With this car, most the time the idle seems too low on a cold start so keep thinking it’s some kind of temperature sensor but the 1.2tsi has sensors all over it.

You need to get diag tool on it to see what codes (if any) it’s setting. The 1.2tsi engine will have a multitude of sensors, coolant temp being just one that could impact the idle speed. If it’s not got a MAF it will have other sensors to measure airflow (MAP & BAP) etc.

Intermittent temp sensor fault sounds plausible. The increasing revs at startup sounds like a normal auto choke effect, so if when this is working the car drives fine this could be that the temp sensor is working.

There will be lots of temp sensors but the PCM might be looking at one and getting a bad reading, but it might not know it’s bad. The car doesn’t necessarily know it’s not 40C outside.

Don’t guess though. A diagnostic tool would tell you the temp sensor reading and you’d know straight away. If you can bring it to or near South Wales I can help.

Nothing was showing on a diagnostic report from the dealer. Would a bad temp sensor show a fault code though?

There will be lots of temp sensors but the PCM might be looking at one and getting a bad reading, but it might not know it’s bad. The car doesn’t necessarily know it’s not 40C outside.

From a cold start the temp sensors will almost always have a crosscheck against other sensors and a temperature soak model within the PCM.

If it was an intermittent temp sensor – which I personally think is pretty likely as well – the above ‘plausibility’ check would flag a fault and should be visible with a scan tool.

A potential side effect of this is that it might inhibit the catalyst heating functionality which is what the raised idle for 20-30s you normally see is. This may well explain why you sometimes don’t see the catalyst heating raised idle – although I would say this would be unlikely without lighting the MIL; this makes the fault ’emissions relevant’ which should light the MIL after 3 successive faults are triggered. How often does the non-raised idle occur?

Nothing was showing on a diagnostic report from the dealer. Would a bad temp sensor show a fault code though?

It should, but there might well be a situation in which it doesn’t show up, some combination of issues. It also should be recorded even if it’s not happening when the scan is done. But I dunno.

Yeah, if it has seen the issue there would normally be a ‘pending’ code. When faults are flagged it’s not usually an instant ‘fault’ but instead the engine management system has to see a certain number of fault events in a row to trigger a real fault; until that happens it is pending. However, the faults also ‘heal’ within the management system if a number of drive cycles occur without the fault… This is usually higher than the number of drive cycles needed to set the fault (e.g. if it’s 3 detections to set a fault, it’s 5 non-detections to clear the pending). So ideally get it to a garage within a drive cycle (ignition on to ignition off with driving in between) of feeling the issue in the car. That will give the best chance of catching the fault on the scan tool.

How often does the non-raised idle occur?

Most of the time. 9 out of 10 times.

Just ran a diagnostics report but no faults were reported. I used the Carista OBD2 reader. Apparently it works with other apps but they all seem the same.

I read about some apps letting you change things like the gear shift points which I’d like to try as it feels like the car is trying to change gear then changes its mind.

Generic OBD2 readers only read the engine ECU I think, and then only some stuff. VCDS or the dealer stuff should give you loads more info.

I read about some apps letting you change things like the gear shift points which I’d like to try as it feels like the car is trying to change gear then changes its mind.

This is an absolutely terrible idea. The shift points are based on pedal position, engine speed and other factors, this is called the gearbox map. If you aimlessly poke about with this then it’ll ruin it, even if you could. There’s an engine fault that needs rectifying – changing the gearbox because there’s an engine fault is arse backwards, because you’ll still have an engine fault!

Generic OBD2 readers only read the engine ECU I think, and then only some stuff. VCDS or the dealer stuff should give you loads more info.

Yeah, OBD is made up of the the stuff that you legally have to output – both data and some faults – and which must be available on any tool, and then manufacturer specific stuff – again, both data and faults – that can be made only visible to the manufacturer specific scan tools or the higher end units/software.

This is an absolutely terrible idea

What he said. Gearbox calibration takes the best part of a year or two depending on how ‘carryover’ the model and transmission are and is a specific role for a manufacturer’s engineering team – just because you can change it doesn’t mean you should or would actually know how to!

It could be a gearbox fault as the problem only happens in 3rd gear. Feels like it trys to change gear then immediately decides not to. Once warmed up it’s fine.

It’s unlikely to be the same fault as what’s causing the engine issues, but of course you could also have a gearbox fault. But I learned that the engine and gearbox communicate closely with each other during a shift so it could still be the engine.

A VCDS will give you gearbox codes.

Does it happen at a similar road speed when in 3rd gear? Could be an airflow issue in that at a certain airspeed into the air intake is causing an erroneous reading leading to the stutter. When the car is warm or does the 1100rpm thing it’s in a different map/mode so it doesn’t occur.

Get it good and warm. Take to dealer – buy new car and partex this one. If it has this problem at such a low mileage and age it’s a wrong ‘un!

Does it happen at a similar road speed when in 3rd gear? Could be an airflow issue in that at a certain airspeed into the air intake is causing an erroneous reading leading to the stutter. When the car is warm or does the 1100rpm thing it’s in a different map/mode so it doesn’t occur.

That’s what I’m thinking. I can only feel the fault in odd numbered gears so thought is was a clutch issue but would have guessed it would be worse when warmed up. And some days it’s fine from a cold start. It happens at different speeds but mostly at 3000rpm and at any throttle position. Happens in D, S, and manual.

Found out something new the last couple of days.

When I start the car, if I turn the key and let go as soon as it fires up it idle at about 900rpm. But if I turn the key and hold it turned for a few seconds before releasing it idles at about 1100rpm.

But if I turn the key and hold it turned for a few seconds before releasing it idles at about 1100rpm.

Why would you do this?

Why would you do this?

When it starts and idles at 1100rpm I dont get the fault for the entire journey. But on days when it starts and idles at 900rpm, all the odd numbered gears are rough and stutter.

Why would you do this?

He has an irrational hatred of his drive pinion and starter ring?

He has an irrational hatred of his drive pinion and starter ring?

I have a love/hate relationship with the entire car. Love the practicality as I can fit 2 bikes inside with fork mounts. But hate how it drives when cold.

The cars 4 years old. 14k miles. 1.2 DSG. In 3rd gear the car kind of stutters at certain rpm. Almost like clutch slip or your foot slips of the throttle for half a second. Doesn’t do it after about 20 mins of driving.

Sometimes, maybe 1 in every 10 days, it doesn’t have any issues at all. That’s when I noticed the different idle speeds.

Dealers dont want to know. Tried and exhausted that one. Independent mechanic could feel the issue but couldn’t diagnose it.

Do you think it could be a trait, and not a fault?

My wife until recently had a 1.2tsi Ibiza, I’ve got a Superb DSG so I’ve got some experience.

Both the Ibiza and the Superb are a tiny bit sluggish when the ambient temp is lower, it’s pretty noticeable this time of year when we get our first cool / damp mornings for a while.

TBH, VW DSG cars, especially petrol’s (my Wife has got a 1.5TSI DSG now) do a great job of feeling very digital in normal use, they don’t feel like there’s anything as archaic a engine under the bonnet, but a millions sensors and computers aside, they’re basically the same tech as the cars of 20 years ago you expected to be a bit sluggish / rough when they’re cold. Only this morning my Superb felt like the engine wasn’t ideally mated to the gearbox when I went up a normally steep include and it couldn’t really decide if it wanted 2nd or 3rd, it also wants to pull off in 2nd (that’s an normal efficiency thing for my car) but it ends up forcefully dropping back to 1st when you need to move a bit quicker than expected. It only does this when the engine is cold. I don’t think anything is really wrong with it, it’s just a mechanical device, one driven by computers that can’t always second-guess you.

My old car used to have something similar (hesitancy when cold, worse cold days etc). I drove around it for years but eventually a light came on and the fault code was for the lambda sensor. When this was changed, it was all fixed.

Though it’s probably just one of dozens of things that could cause similar behaviour.

I dont think it’s a trait as it’s only affecting the odd numbered gears. Not really sluggish but the power is on/off/on/off for a couple of seconds at certain rpm. Only in 3rd and 5th. Some days it’s fine. Most days it’s not and it’s getting worse.

After about 20 mins of driving it works brilliantly. But most my journeys are 20 mins. My last car (Fiat) had a larger engine and never suffered while warming up. I dont drive hard, and never floor it when warming up.